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1 <chapter>
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2 <title>C System Calls</title>
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3 <para>
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4 This section of the C compiler manual is a guide to the system
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5 calls available from C programs.
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6 </para>
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7 <para>
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8 It is <emphasis>not</emphasis> intended as a definitive description of OS-9 service
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9 requests as these are described in the OS-9 System Programmer's
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10 Manual. However, for most calls, enough information is available
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11 here to enable the programmer to write systems calls into programs
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12 without looking further.
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13 </para>
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14 <para>
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15 The names used for the system calls are chosen so that programs
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16 transported from other machines or operating systems should compile
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17 and run with as little modification as possible. However, care
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18 should be taken as the parameters and returned values of some calls
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19 may not be compatible with those on other systems. Programmers that
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20 are already familiar with OS-9 names and values should take
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21 particular care. Some calls do not share the same names as the OS-9
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22 assembly language equivalents. The assembly language equivalent
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23 call is shown, where there is one, on the relevant page of the C
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24 call description, and a cross-reference list is provided for those
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25 already familiar with OS-9 calls.
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26 </para>
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27 <para>
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28 The normal error indication on return from a system call is a
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29 returned value of -1. The relevant error will be found in the
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30 predefined int "errno". Errno always contains the error from the last
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31 erroneous system call. Definitions for the errors for inclusion in
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32 the programs are in "<errno.h>".
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33 </para>
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34 <para>
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35 In the "See Also" sections on the following pages, unless
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36 otherwise stated, the references are to other system calls.
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37 </para>
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38 <para>
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39 Where "#include" files are shown, it is not mandatory to include
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40 them, but it might be convenient to use the manifest constants
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41 defined in them rather than integers; it certainly makes for
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42 more readable programs.
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43 </para>
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466
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44 &abortref;
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45 &absref;
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46 &accessref;
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47 &chainref;
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48 &chdirref;
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49 &chmodref;
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50 &chownref;
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51 &closeref;
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52 &crcref;
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53 &creatref;
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54 &defdriveref;
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55 &dupref;
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56 &exitref;
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57 &getpidref;
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58 &getstatref;
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59 &getuidref;
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60 &interceptref;
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61 &killref;
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62 &lseekref;
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63 &mknodref;
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64 &modloadref;
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65 &munlinkref;
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66 &os9ref;
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67 &openref;
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68 &os9forkref;
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69 &pauseref;
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70 &prerrref;
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71 &readref;
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72 &sbrkref;
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73 &setprref;
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74 &setimeref;
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75 &setuidref;
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76 &setstatref;
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77 &signalref;
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78 &stacksizeref;
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79 &strassref;
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80 &tsleepref;
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81 &unlinkref;
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82 &waitref;
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83 &writeref;
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84
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85 </chapter>
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